Fallax Iuvente
by Kami-no-Namida
Summary: Severus Snape and Harry Potter never got along. After a failed attempt of Occlumency lessons the words applied all the more. However it might take one failed potion to change it. To uderstand the other's pains better. They might find friendship in each other... or maybe even love? De-Aging, Mentions of child abuse, Slash, Mpreg (possibly), Rated T for now
1. Illusive Youth

Hi there (^^)/

Another year gone, I'm starting a fic as a birthday gift to myself again~

(_As almost always_) I'm keeping the basic line up to 4th book, then, though the basic is the same, I'll play with the content a bit. I will explain all the changes along the way, so hopefully you won't get lost (-w-')

I am sorry to all you who are waiting for my updates, I will try to update as fast as possible. I love you (0w0)/

**Warning:** De-Aging, Mentions of child abuse_ (& some flashbacks tied to it) __**Later on**_: Slash, Mpreg _(possibly)_... nothing else I can think of for now

**Disclaimer:** I don't own Harry Potter, J. K. Rowling does... Lucky her... (QmQ)

* * *

**…** **Fallax Iuvente …**

**1. Illusive Youth**

_It was cold in the castle when Harry went to the dungeons with his friends. That however_ _was nothing out of ordinary._

_Everything seemed peaceful and normal._

_Monday the thirteenth, a day which was to be followed by Valentine's, truly might have seemed that._

_It however was mostly because of that perspective, which everyone seemed to have, that Harry felt confused about warning bells going off in his head. He simply could not shake off the feeling of dread, it increasing on intensity when he saw the group of students in red and green colours pour inside the just opened Potions classroom._

_There was something about the day which made Harry feel more than slightly uneasy. A strange feeling of expectation irking his senses._

_Just how the first lesson of the week was to turn out though, he could everything but expect._

...

"The potion we shall be brewing today is not a time-consuming one, it however is quite complex. Be it as may, it still is one a competent fifth year should be able to do halfway through the year." Snape started talking as soon as he swept into the classroom, his cloak billowing behind him.

"The potion is called "Fallax Iuvente", which means "Illusive Youth"." the professor lectured, walking through the classroom. "It makes the one who drinks it younger by half his age for a few hours if brewed correctly. Not that I expect many of you to achieve that." the Potions Master sneered as his eyes swept over the class of joined Gryffindor and Slytherin fifth years.

"You will be working alone, the instructions are on the board." Snape said as he strode to his desk in the front of the classroom. "You better be careful with it, it can get into your system through skin also and I have no need of screaming brats here... not that most of you are any better now." the black eyes slid critically from one side of the class to the other again, then back to where Gryffindors sat, the gaze staying there significantly.

"Now, I believe I gave you a work to do. Whoever does not manage to brew a decent potion - asking perfect would be too much - until the lesson is over will be repeating the process with me during a detention... and will do so for as long as it will get you to do it right. Understood?"

A lukewarm "Yes, sir." rang through the class, soon followed by scrapping of the chairs as everyone decided they better not anger Snape by not getting to work quickly enough.

And so the class started.

...

It was a normal Potions lesson and as such there was an accident almost sure to occur.

If asked it would also be no wonder as to with whom the source of the chain reaction was to be found.

After all who else to commit an error in the class of the feared teacher if not Neville...

...

_"Longbottom,_ you thorn in my eye, what do you think you're about to add to that potion?" voice of one Severus Snape rang through the dark, dungeon classroom.

"Where is it written in the instruction that you should add dragon scales to the potion now? Where is it written that you'll even need them _at all_?"

At the teacher's words Neville paled considerably and retreated his hand which was about to drop the scales into the potion and few of the Slytherins snickered. Needless to say both of that increased on intensity when the teacher strode closer to the Gryffindor's workplace.

"These are not needed, neither are these... Valerian roots? Sopophorous beans? Are you preparing a Draught of Living Death Longbottom?" saying that the two ingredients were sent with a wave of wand back to the ingredients storage.

"You have somehow managed to add right ingredients, even if completely out of time and not prepared according to the instructions... For that I'll take five points from Gryffindor for cheating. I am sure Miss Patil knows that it is something I do not tolerate in my class." Snape's eyes slid accusingly to the young witch who only turned her eyes away, knowing better than to protest. She _did_ help Neville after all... even if it was more of a self-defence with the boy sitting just behind her... Not that having Snape behind her back as of that moment was any better.

"Now you take all those excess ingredients back to the storage and sort them properly. _Properly,_ I say, it's not like you'll escape the detention to redo the potion anyway... better not add to it, right?" the teacher narrowed his eyes at the boy, scaring him effectively.

"Ye-yes s-sir" Neville stuttered out as he paled to almost invisibility. He then got up and took the wooden board on which all the unneeded ingredients were.

Being increasingly clumsy when nervous Neville however did what most may have suspected, he stumbled and fell... causing half of the ingredients from the board to fall into the cauldron.

As Snape stood than a a meter away still, he saw the incident firsthand, and was glaring at Neville who still did not manage to even get up, already dreading the teacher's reaction.

"What do you think you're doing you..."

What creative insult the Potion's master wanted to use, however, no one got to know. For it was in that very moment that the cauldron exploded... its contents drenching the professor from head to toe.

...

Harry, who was sitting three desks away, as well as rest of the class were waiting for the screaming to come... However when it did, it was in a form no one expected.

For those were not screams of anger.

They were screams of pure, _agonizing_ pain.

Soon the professor was writhing on the floor, which someone managed to clean up with a spell in a moment - someone from Slytherin probably.

It was about at that time also that a bushy-haired girl who sat next to Neville in the last row - one of the reasons for the class not to be affected, for the professor got to be an unwilling shield of sorts - ran to get Madame Pomfrey.

It was however sooner, than when the medi-witch of Hogwarts came, that the results of the potion shown themselves.

There, on the potions classroom floor, sat a very small, sobbing, and all in all very much confused version of one Severus Tobias Snape.

* * *

**So? What do you think? (o.o) I'm curious. _(Did you expect the young-ed one to be Harry?)_**

**It's short, I know, but my 1st chapters usually are... I promise they will get lengthier. (^^)**

******See ya~ ( "-.-)/**


	2. The Boy Who Refused to Let Go

**…** **Fallax Iuvente …**

**2. The Boy Who Refused to Let Go**

The Gryffindor-Slytherin class stood frozen as a whole as they were processing what has happened to their professor. It was needless to say that none of them expected to see what the Gryffindor boy, who had yet to get up from the floor, caused. A boy who was already seeing the Death's welcoming arms in his mind, imagining what the professor in question would do to him once set right.

"What happened here?" a voice of the school's medi-witch broke through the tension as the woman herself barged into the room... An action which caused the childified professor to burst out in tears.

"Oh my, who is that?" the school's medi-witch asked, guessing what had happened, as she came closer. She did not even have to have her question answered, because the black robes which hung on the child and which she noticed only when coming closer more than gave it away. "Severus?"

At the sound of his name the crying boy turned to the woman who crouched to be on his level, however the end of the streams of tears seemed nowhere in sight.

"Neville's cauldron exploded and Professor Snape was standing right in front of it." Hermione supplied, having come back with the older witch.

"I see." the medi-witch mumbled to herself, running her wand down the child's small form, searching for injuries. "He did warn me that a potion with ability to de-age someone was to be brewed today, I however did not expect him to be the one who would end up in this predicament."

"I don't think Snape planned it either." Harry, who inched closer, said. The chiding look from he earned from Hermione told him she was not exactly happy about his input.

Harry was the only one who was advancing closer, the rest of the joined class of snakes and lions seemed to think that getting as far as possible was in their best interest as of that moment. Harry however thought that doing that was only serving to scare the child further.

"Is he going to be alright?" Hermione asked Madame Pomfrey as the witch finished her scan.

"I will have to bring him to the Infirmary, the potion was not supposed to regress someone in age so far." she declared in a grave tone.

"One of the reasons the potion is only cutting someone's age in half is because no one found a way to accomplish more without it having some side effects... As you can see having regressed in mind, aside from the body, is one of them. Correctly brewed _Fallax Iuvente_ should leave the drinker with their older mind, it wouldn't be of much use otherwise. At the top of that I also need to run a full-body check spell to estimate what age he is now." the witch sighed as she stood up.

The little boy got startled by the sudden movement and wanted to back up, he however only managed to trip on his long oversized robes and fell back... straight into Harry who by then was right behind him and caught him before he fell on the ground.

The dark eyes of the child turned up and locked with the green, the tears forgotten for a fraction of a moment.

Harry almost waited for some scathing remark of his professor to fall from the child's lips. Instead of that however, the boy turned and hid his face in Harry's robes as he started crying again.

Harry looked up from he shaking little form to the two witches who saw what had happened, only to see mixed expressions of shock and bemusement.

"Now that was unexpected." Madame Pomfrey laughed softly.

"I suppose you can carry him then, he does not seem opposed to the idea." she added after she tried to take her de-aged colleague herself, which resulted in him crying harder and gripping Harry's robes tighter, the knuckles of the small hands turning white.

"If you think so..." Harry forced out of himself, taking his professor up into his arms and had him wrap the short arms around his neck. Only idly did he note the too big shoes and trousers - along with his undergarments, Harry discerned with a flush - falling to the ground as he did so, the rest of the clothes hanging loose on the boy.

"So, shall we go?"

...

The trip to Infirmary was... _long._ And exhausting.

There was no other way to describe it as far as Harry was concerned.

It was not that the small body in his arms was heavy or anything, as a matter of a fact Harry thought that the black robes hanging on the scrawny boy were heavier than the child itself. No, it was more that _mysteriously_ there were all too many people around the Hogwarts' corridors. _Everyone_ somehow knew what had happened in the Potions lesson of the Fifth years'. The fact that their Potions professor was carried to the Infirmary by the Boy-Who-Lived only served as even more a flame to the moths who kept on gathering.

'Where is a Floo connection when someone needs it?' Harry thought grumpily as he heard yet another gasp as he passed. He was growing steadily uneasy, as he always did when in a bigger crowd. Mostly because having so many people around was bringing a lot of bad memories. The latest of them being from the time certain pink toad, who was to oversee the school, had rounded up on DA... and those memories brought _only_ unease... there were some which were much, _much_ worse. Like the one where the crowd had flashing cameras, all of them wanting to know what had truly happened at the graveyard.

'As if being accused of spouting lies and madness had not been enough.' Harry thought, the sentence carved into his hand itching.

'If nothing else, at least we don't have her here still...' Harry thought, deciding to keep his mid on the lesser of two evils. It was already two months, it having happened at the start of December, since the Inquisitorial squad of Umbridge's found out about DA and caught them in the Room of Requirement.

Wanting to prove that she has the most power, Umbridge threatened with detentions, expulsions and spells to have them spill information, the latest not once the Minister appeared, called by whom, Harry did not know, but the threats continued. Harry did not mean to let it slip, but once he mentioned the quill the woman used on him, Umbridge paled. Dumbledore and Minister both wanted to know what he meant by that and when he elaborated Umbridge soon had her ticket out of the school... and into Azkaban.

'Seems the Blood quill really is a Dark artifact, huh... Should not be much of a surprise.' Harry thought back to that moment, glancing at the scars on his hand, despite it being a bit hard with his cargo.

The only good thing that came out of that unpleasant memory was the celebration in the woman's... dishonor which had been held after she had been taken away by Aurors. The only ones who did not seem to enjoy themselves that day were the student members of the Inquisitorial squad - who got a month of detentions each - and Filch... if the way he glared at everyone all the more intensely up till that moment was anything to go by... It was.

'What would she be doing to Snape if this happened whilst she was here? Well, if she allowed for such a potion to be brewed.' Harry wondered briefly, 'She would probably make him leave even as a child of what ... three years, maybe?' The image of that was not even humorous. The idea of literally leaving a little boy out in the cold was awful, despite the boy being a child version Snape.

Harry himself remembered well how staying nights outside in the cold - and with little to no clothes - felt. He would not wish it on anyone. Not on Snape. Not on people he hated, the professor not belonging among those for some time already. Dislike, maybe, but hate... There was a different being Harry associated that emotion with.

'Maybe if, instead of killing him, we left Voldemort out in the cold for an hour - or a day - then maybe his ego would freeze down a little.' Harry chuckled to himself, imagining the almost-reptile in the snow. 'But don't snakes hibernate in the cold or something?'

As Harry elaborated that idea in his head he and Madame Pomfrey reached the Infirmary.

...

"Could you please put him down on that bed?" the matron asked as she pointed to the bed closest to her office as she left through another door. Harry complied quickly... or at least tried to. For some reason little Snape did not want to let go of Harry, and only held on tighter.

"Oh, come on." Harry sighed as the bare feet hit the bed. "I hope you don't plan on hanging onto me for the remainder of the day." he added when the child backed up a bit to steady his footing, coming face to face with Harry.

Seemingly understanding the boy eased the deathly grip around Harry's neck... He however found out that with holding onto Harry's robes the Gryffindor could not do much to leave either. And hold them he did and so Harry only sat on the bed next to him.

"Ah, I would never take Severus for much of a clingy person." Madame Pomfrey, who by then emerged from what could only be the Infirmary storage with some potions, said with a smile as she was coming closer.

"Try saying that when you're on the receiving end of it." Harry said through gritted teeth of a forced smile as the presence of the woman scared the boy enough to hide his face in the fold of Harry's robes again.

What seemed to be dislike for his person in Harry's voice upset the boy enough to start another wave of tears, which quickly started to soak into Harry's robes, which the childified professor refused to let go of even so.

"Aw, come on..." Harry petted the black-hair-covered head awkwardly, placing his other hand over the small fists with white knuckles. "I didn't mean it like that, you don't need to abuse my poor school robes."

Harry almost snorted when he realised just how that situation must look from the outsider's point of view, him soothing the shrunk version of their Potions professor whom most of the school hated. Oh, joy.

"You're so going to make my life a living hell once you remember how this day went." Harry continued his monologue, as he petted the black hair with more of an ease, the boy not having spoken a word as of yet. But yeah, Snape never was a talkative person to begin with.

Before Harry even noticed it the child which wormed his way into his arms again had fallen asleep, tiny droplets of tears still clinging to his lashes, some still lazily making their way down the boy's cheeks. Harry gently brushed them off and could only marvel just how much of a different yet similar and familiar face he was seeing.

The dark irises of the boy's eyes, which were now hidden by black eye-lashes. The nose which was, so far only slightly, bigger than some would think aesthetically agreeable. The ink-black hair framing the pale face... It was strange, if nothing else, to see the skin unmarred by the years... Of struggles. Of bitterness. Of pain...

"So much has changed." Harry muttered to himself as his finger traced the corners of the eyes, where wrinkles were in high numbers on the older face.

"It's astounding, isn't it?" Madame Pomfrey remarked, causing Harry to jump as he has pretty much forgotten her presence by then. "And to think poor Severus is not even his fourties yet."

Harry did not know what to make of that information, but decided that not commenting on it would be the best way to go.

It was.

...

"Harry, my boy, in the Infirmary again?" the cheerful voice of the Headmaster brought Harry out of his reverie. He had been zoning out a bit during the second round of Madame Pomfrey's check up on the professor who still had a deathly grip on his robes.

"Not my fault this time." Harry sighed, seeing the light of the medi-witch's wand start to fade. "And it's not even my fault Snape is here."

_"Professor_ Snape, I have to remind you. Who seems to be the source of Severus' _predicament_ then?"

"Neville." Harry snorted. Because really, who did Dumbledore expect it to be, Malfoy? "The only saving grace is that he only has to pass OWLs for Potions, after those he can drop it."

"Mr. Longbottom, I see..."

'As if you didn't know.' Harry chuckled inwardly.

"... And Severus was on the receiving end of the explosion why?"

"He was commenting on Neville's potion and probably preventing the thing from turning into acid or something, also decking some points... Either way Neville fell and some of the ingredients he was taking away fell into the cauldron... and it exploded pretty much into Snape's face."

_"Professor_ Snape, Harry." The elderly man sighed. "But the turn of events is unfortunate. Not to mention that with our resident Potion's master incapacitated... We'll have to wait the effect of the potion out. Hopefully it will fade quickly. The original _Fallax Iuvente_ is supposed to last only a few hours, if my memory serves me well still... If the effect does not fade by then, we will have to make arrangements."

"What arrangements?" Harry could not help but keep his curiosity in check.

"We'll cross that bridge once we got to it, Harry, my boy. Now Poppy, I believe you finished your report?"

As the Headmaster's attention turned to the witch, so did Harry's... and so did the attention of the boy who just woke up.

"As far as I can tell Severus appears to be three years and roughly four months old." the witch started, Harry noting with amusement that the boy who was all but sitting in his lap held three tiny fingers up at the words.

"Yeah, exactly that many." he smiled, holding the child's hand back down, letting the elderly witch continue.

"He does not have any burns from the explosion, but we should probably monitor him, because it is likely that those will appear once he is set back into his correct age." she continued, her eyes not straying from what she had written on the parchment before her.

"He seems a bit underfed, but I can't figure out the reason why, aside from guessing that this was how he had been back at that age." she explained, looking up at her colleague. "Aside from that and few bruises which I assume fit into the time setting of his body, there is nothing else wrong."

"Thank you Poppy." Dumbledore smiled at his long-time friend as he sat down on the hospital bed next to Harry, looking at the black-haired child who still refused to let go of Harry's robes.

"Severus, my boy, what am I supposed to do with you?" the wizard sighed as he waved his hand and the clothes which still hung on the child were transfigured into ones much more appropriate for someone at the age of three.

Harry could not help but smile softly as he looked the clothing in pastel colours, thinking that the older version of Snape would probably have a stroke if he saw. His smile however disappeared when he saw that the eyes of the Headmaster were lacking their usual twinkle as he took in all of the changes the Potions professor went through. It was a sure sign that the situation was not going to be easily solved.

"He isn't going to stay like this, is he?" Harry voiced one of the options which formed in his head. It was that, or Snape going back to normal, which was pretty unlikely, given that the potion _had_ been botched after all.

"I would rather not even think of that option, my boy." the Headmaster avowed. "For I hope that this is only temporary. That soon we will have our resident Potions Master back. If the stars were looking in our favour, he would be back as soon as tomorrow."

Except he was not.

...

Harry woke up in the Infirmary a bit disoriented, for he did not remember falling asleep.

The light shining through the tall windows however told him that he must have slept right through into the next day. Was it strange to no one that he did not come to the dormitories or what?

"Harry!"

'Ah, not so invisible then.' Harry snickered to himself as he saw Hermione approach.

"Hi there, Hermione." he greeted his friend as he sat up a bit in the bed. When had someone put a blanket over him?

"Professor McGonagall told us that you had to stay here." Hermione started speaking as soon as she was standing next to the bed. "We were worried about what happened Harry and..."

"Hawwy!"

The Gryffindor nearly jumped a metre at the unexpected voice next to him. As he turned around, he could only think that he should be anything but surprised.

"Hawwy!" the still-child-like professor spoke again as he caught the Gryffindor he was speaking to by his robes yet again.

"You're such a little leech." Harry snorted as he ruffled the black hair, which reached just to the boy's jaw, into a bird's nest. He then retreated his head astonished as he realised what he had just done.

"Hawwy?"

"You're so going to kill me when you turn to normal." Harry mumbled under his breath, so softly that only Hermione heard it.

"You actually hate me, do you know that?" he added as he straightened the hair back into a resemblance of a normal hairdo. Then retracted himself off the bad so the boy could not reach him anymore.

"Hawwy no like Sevvy?" the boy sniffed as he reached his little hands out to Harry. It was quite a pitiful sight actually.

Hermione watched the puzzled feelings Harry had over that statement and she could not really blame him. She would not know what to do were she in the same situation, but then again, she never had problems with professors much. And if there was one professor Harry had conflicted feelings about, it was Snape. Ever since those Occlumency lessons ended Harry had been talking differently about the man. Not _nicely,_ but differently.

As Hermione assessed the situation and Harry still was having an inner conflict over whether he should or should not go closer to the little boy, the sniffling of one Severus Snape, child version, turned into a full-blown wail.

And with that Harry's resolve crumbled as he sat down onto the bed and gathered the weeping child into his arms.

"Sevvy be good." the boy cried into Harry's shirt. "Sevvy is not doing bad things. Why you no like Sevvy?"

"Bad things?" Harry mouthed at Hermione, as he stroked the boy's head, only to have the girl shrug her shoulders.

Harry knew what had been considered "bad" and "freakish" when _he_ was growing up, but wasn't Snape a half-blood at least?

"It's okay. You're being good. There's nothing wrong with you." Harry whispered softly into the boy's soft hair. He hoped he had someone to tell him this when he had been that age. When the magic first started to show itself... But that was not to be.

...

"He was not always a professor, you know?" Hermione gave her comments once Harry lulled the boy into sleep. The boy who yet again managing to get a white-knuckled grip on his robes.

"I _know_ that, but it's so strange. On one side he's Snape, the professor most of the school loves to hate and who went to school with my parents and..." 'Who had been bullied by his peers, the same as I was...' Harry added to himself.

"And on the other he's here as this child, completely stripped of all those years, innocent of all of them, attached to me for no apparent reason and lisping my name cutely as if it was the most normal thing in the world." Harry groaned. "Just how wrong is it to find the lisp cute?"

"There's nothing wrong on it Harry." Hermione put her hand on his arm as she sat down on the bed next to him. "The thing is that you have to allow yourself to accept that."

"Yeah, I guess you're right." the teen sighed yet again, his hand stroking the soft black hair of the professor still.

"I'll go and get Headmaster, he told me to inform him if there was no change with Professor Snape, though I doubt the portraits haven't told him yet. Either way he said that he'll come down and see for himself." Hermione said as she stood up, sweeping an imaginary dust off her robes. "Will you be okay?"

"Yeah." Harry smiled at her, then looked down at the child who was still sleeping on his lap, the grip on his robes only in the sleep slackening slightly.

"I think I will be."

* * *

**Here it is (0w0) A new chapter! (O0O)/**_(and three times the length of the first one, yay! °(0w0)°)_

**Sorry to have kept you waiting for so long. (^^') The school has started after all, and with five ongoing fanfictions and real life making mess of my schedule at once, I found myself with not much time to spare... but yeah, anyway. I hope you enjoyed, despite the lateness, hopefully the next chapter will come sooner. (o3o)/**

**Constructive criticism welcomed. (^^) Review, please? o(O.O)o**

**See ya~ ( "-.-)/**


End file.
